<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>01-CSS入门基础知识</title>

    <!-- 派生选择器 通过依据元素在其位置的上下文关系来定义样式 -->
    <style type="text/css">
        ul li strong {color:#bf0000;}

        #container{background:#333333;}
        #container a {color: #bf0000}

        .bg{
            width:300px;height: 200px;
            background:  url("images/bg.jpg") no-repeat ;background-position: -93px -144px;
            /*background-origin: content-box;*/
            /*background-clip: content-box;*/
        }

    </style>
</head>
<body>
    <p> <strong> p标签 strong </strong> </p>
    <ul><li> <strong>li标签strong</strong> </li></ul>
<div id="container">asdasdads <a>ID选择器与派生选择器混用</a> </div>

<div>
    <p class="bg"></p>
</div>


</body>
</html>